Delivery elevator for printing press and control therefor



J. F. BLAHA Nov. 14, 1961 DELIVERY ELEVATOR FOR PRINTING PRESS AND CONTROL THEREFOR I Filed Nov. 14, 1960 IN V EN TOR. Jaw/v F 62 A HA A TTOR/Vf Y5 United States Patent C) M of Delaware Filed Nov. 14, 1960, Ser. No. 69,140 7 Claims. (Cl. 271--88) The present invention relates to apparatus including an elevator on which sheets are stacked to form a pile, more particularly to a printing press delivery including such an elevator, and including a control for effecting the lowering of the elevator when the pile thereon reaches a predetermined level; and, more particularly, to a printing press delivery embody-ing such an elevator and control.

Various types of photocell controls have been provided for effecting the lowering of an elevator upon which sheets are being stacked, such as the elevator in the delivery of a printing press, and it is an object of the present invention to provide a new and improved device in combination with such an elevator for sensing when the pile thereon reaches a predetermined level and signalling the lowering of the elevator.

It is further an object of the present invention to provide in combination with the elevator upon which sheets are being stacked a sensing device of the type in which the sensing operation is performed by the breaking of a direct beam of radiation by the pile, the device being reliable in operation, compact, and less subject to false or premature tripping when used in combination with an elevator on which sheets of relatively light material are being stacked by dropping the sheets onto the elevator from above.

It is another object to provide a printing press delivery having an elevator upon which the sheets being delivered are stacked and an end gate against which the edges of the sheets forming one side of the pile are stacked, the end gate being operable between a stacking position and an open position to permit removal of the top sheet outwardly of the side of the pile engaged by the end gate and the pile level detecting means being located adjacent the side of the pile engaging the end gate and being supported so that it does not interfere with the removal of the sheets through the end gate.

It is a further object of the present invention. to provide in combination with an. elevator in the delivery of a printing press a pile level detecting device of the direct-beam type which is not subject to false or premature tripping by bulges in light flexible sheets as the sheets are dropped onto the elevator, and which is so located that it requires little or no adjustment for different size sheets and does not present an interference problem with the jogging apparatus and other devices normally used with the delivery of a printing press or with the removal of a sheet through the end gate of the delivery.

Further objects and advantages of the present invention will be apparent from the following detailed description thereof made with reference to the accompanying drawings forming a part of the present specification and in which:

FIG. 1 is a fragmentary side elevational view of a printing press delivery embodying the present invention;

FIG. 2 is a fragmentary perspective view of a'portion of FIG. 1 but on an enlarged scale;

FIG. 3 corresponds to FIG. 2 with certain parts shown being located in a position dilferent from those of FIG. 2; and

FIG. 4 is a simplified electrical circuit which may be used with the present invention.

While the present invention is susceptible'o-f various constructions, modifications, and arrangements and of 3,008,710 Patented Nov. 14, 1961 use with various types of elevators upon which sheets are being stacked, it is particularly useful when embodied in the delivery of a printing press to control the lowering of the delivery elevator when the pile thereon reaches a predetermined level and is herein shown as embodied in such a delivery.

In accordance with one feature of the present invention, the level of the pile of sheets on the delivery elevator of the printing press is sensed by a device which emits a direct beam of radiation that is broken to perform a control operation when the pile reaches a predetermined level, the beam of radiation being directed across one corner of the pile so that the device is not subject to premature or false tripping by bulges in the sheets which are being stacked on the elevator. Furthermore, the pile level detecting device is mounted adjacent the side of the pile which is stacked against the end gate of the delivery so that the device need not be adjusted each time different length sheets are to be delivered to the elevator, and in the preferred embodiment, the detecting device is moved, with the end gate when the latter is opened, from a detecting position which would normally interfere with the removal of a sheet through the end gate to a position which permits the removal of the sheet.

Referring to the drawings, the delivery shown therein is a known type of delivery and may be the delivery shown in Patent No. 2,673,735, issued March 30, 1954, to I. F. Niles et al. The delivery includes a chain conveyor 10 which delivers sheets from the printing press to a position over a delivery elevator 11 and as the sheets are carried to a position above the elevator, the sheets are released by the conveyor 10 and dropped onto the elevator. When the sheets are released, their forward momentum may carry them against a conventional end gate 12 so that the leading edge of the sheet as it moves from the printing press is stacked against the end gate. The endgate 12 functions to even the side of the pile formed by the leading edges of the sheets and designated by the reference numeral 14. Conventional joggers may be provided adjacent each of the other sides of the pile to jog the sheets into their correct positions against the end gate and to even all other sides.

As the pile of sheets builds up on the elevator 11, the elevator is lowered to prevent the sheets from stacking into the chain conveyor 10. The mechanism for operating the elevator 11 has not been shown and will not be described, since it may be of conventional construction such as of the construction shown in the Niles et al. patent, except as hereinafter noted, or of a structure similar to that shown in Peyrebrune Patent, No.. 2,525,311. These patents basically utilize a reciprocating pawl, which is normally held out of driving relationship with a mop erating ratchet wheel, to efiect the lowering of the elevator and when the elevator is to be lowered, the pawl is dropped to a driving position to effect a rotation of the ratchet wheel for each reciprocation of the pawl to effect an incremental lowering of the delivery elevator.

During the printing operation, it is often desirable to remove a sheetfrom'the delivery so thatthe printing may be inspected. To this end, the end gate. 12 is movable between a stacking position, wherein the sheets are stacked against the end gate, to an open position. In the disclosed embodiment, the end gate comprises a rockshaft 16 which extends across the delivery parallelto the top edge of the side 14 of the pile and aplurality of fingers 17 depend downwardly from the rockshaft 16 and provide a surface against. which the sheets are stacked. The rocking of the shaft 16 rocks the fingers from a vertical position, as shown in FIGS. 1 and 2, toward a generally horizontal position shown in FIG. 3. In the open position, a sheet can be removed by moving 3 the sheet outwardly of the side 14 through the open end gate.

In accordance with one feature of the present invention, the level of the pile on the elevator is detected by pile level detecting means which is located adjacent one of the corners of the pile adjacent the end gate 12 and is normally in a position which would interfere with the removal of a sheet through the end gate and is supported for movement with the end gate from a detecting position to a position clear of the path of movement of a sheet through the open end gate. The pile level detecting device is designated generally by the reference numeral 20 and, as illustrated in the drawings, comprises a bracket 21 which is adjustably supported on a rod 22 depending from a collar 23 fixed to the rockshaft 16 of the end gate 12. The bracket 21 is disposed adjacent the near lefthand corner of the pile, as the pile is viewed in FlGS. 1 and 2, and includes an arm 25 which extends along the side 14 of the pile adjacent the top edge thereof and a second arm 26 which extends along the front side of the pile as the pile is viewed in FIG. 1 and which intersects the side 14- to define the near left-hand corner of the pile. The arm 26 of the bracket 21 has a radiationemitting device 27 mounted thereon which, in the preferred embodiment, is a lamp that directs a beam of lightacross the corner of the pile to a light-sensitive element 30 mounted adjacent the outer end of the arm 25. The radiation-sensitive element 30 may be any device which has a characteristic which varies in accordance with the amount of radiation impinging thereon, such as a photoconductive resistor or a photoemissive cell when the radiation is light. When the pile of sheets on the elevator reaches the level of the beam, the beam will be broken to signal that the elevator is to be lowered. It will be noted that, inasmuch as the beam is directed across a corner of the pile, the bulging of the sheets in the center of the pile when air is trapped will not efiect a false or premature tripping of the level detecting device. Furthermore, the directing of the beam across a corner of the pile enables the radiation-sensitive device and the radiation-emitting device to be located in an area which does not interfere with the jogging apparatus or other mechanism normally associated with the delivery of a printing press, and the location of the device at the corner of the pile which is defined by one of the sides which is stacked against the end gate eliminates adjustments that would be necessary for different length sheets if one of the corners at the opposite side of the pile from the end gate were chosen.

The mounting of the detecting device for movement with the end gate between a detecting position and an open position moves the arm 25 of the bracket 21 from a position where the arm 25 would normally interfere with removal of the end sheet to a position where the top sheet can be removed without interference from the arm 25, as is evident from FIGS. 1 and. 3.

Furthermore, the disclosed radiation-detecting device may be conveniently used to effect the lowering of the elevator at the discretion of the press operator. It will be noted that if the end gate is swung to an open position, the light beam will be swung downwardly into the pile and will be broken to effect the lowering of the elevator, and when the rockshaft 16 is moved to close the end gate, the beam will be re-established to stop any further lowering of the elevator until the beam is again broken.

If preferred, only the arm 25 could be carried on the rockshaft and the arm 26 made separate and stationary. It can be seen that the opening of the end gate would then swing the arm 25 to move the receiving device 30 out of the light path to break the beam.

A simplified circuit for use with the present invention is shown in FIG. 4. Preferably, a relay coil 36 is connected in series with the radiation-sensitive device 30 across a source of DC. potential. The radiation-sensitive device is preferably a photoresistor that has a relatively high resistance when subjected to a low light level and a relatively low resistance when subjected to a high light level. As long as the beam of radiation strikes the radiation-sensitive device, the relay will remain energized. If, however, the beam is broken, the resistance of the photoresistor increases to a point where the level of the current in the circuit is too small to maintain the relay in an energized condition and the relay drops out. The relay may control the energization of a solenoid for holding the previously mentioned pawl of the type shown in the aforesaid Niles et al. patent or the aforesaid Peyrebrune patent clear of the ratchet wheel and actuatable to eitect the lowering of the elevator by dropping the pawl. As hereinbefore stated, the particular mechanism which the relay controls for effecting the lowering of the elevator may be any known or conventional mechanism and does not, per se, form a part of the present invention.

Preferably, the relay coil 36 has a capacitor 37 connected thereacross. The action of the capacitor will prevent the relay from being tripped when a single sheet passes through the beam as the sheet falls onto the pile. The capacitor will normally be charged to a voltage equal to the voltage drop across the relay and when the current level in the circuit drops momentarily due to the darkening of the radiation-sensitive device, the charge on the condenser will maintain the relay energized for the brief interval during 'Which the beam is interrupted due to the passage of a single sheet.

From the foregoing, it can be seen that the present invention provides a new and improved control for efiecting the lowering of an elevator upon which sheets are being stacked, with the control being particularly adaptable for use in the delivery of a printing press, and being so constructed and arranged that it is not subject to premature or false tripping by bulges in the center area of the sheet due to air trapped under the sheet as the sheet is dropped onto the stack, and it is so constructed and arranged that minimum adjusting is necessary for different size sheets being stacked and is mounted in such a manner that it does not interfere with other elements normally associated with the delivery or with the removal of test sheets from the delivery.

While the preferred embodiment of the present invention has been described in considerable detail, it will be appreciated that the appended claims are intended to cover all constructions, modifications, and arrangements which fall within the ability of those skilled in the art and within the scope and spirit of the present invention.

Having described my invention, what I claim is:

1. In a delivery mechanism including an elevator upon which sheets are stacked in a pile and which is to be lowered when the stack thereon reaches a predetermined level, and an end gate against which the sheets are stacked as they are piled onto said elevator, said end gate being rockable from a stacking position to an open position wherein a sheet can be moved from the top of said pile outwardly away from the side of the pile normally engaging said end gate, pile height detecting means for detecting the building of the height of said pile to a predetermined level including a part for eifecting the sensing of the pile level, which part is disposed in the path of movement of a sheet when moving from the top of said pile through the open end gate, and means mounting said part of said pile height detecting means on said end gate for movement therewith upon the opening of said gate from a detecting position adjacent said sheets to a position clear of the path of a sheet being removed through the open end gate.

2. In a delivery mechanism, the structure as defined in claim 1 wherein said detecting means comprises a radiation-emitting device and a radiation-sensitive devce and said means mounting said detecting means supports one of said devices adjacent said side of the pile and the other of said devices adjacent the side of said pile defining a corner of the pile with the first-mentioned side and the radiation from said radiation-emitting device being directed across said corner to said radiation-sensitive device.

3. In a delivery mechanism, the structure as defined in claim 1 wherein said end gate comprises a rockshaft extending parallel to the first-mentioned side of said pile adjacent the upper edge thereof and a plurality of fingers extending outwardly from said rockshaft and against which said sheets are stacked, and said means mounting said detecting means comprising a bracket having an arm mounting said part and extending along the side of said pile adjacent said end gate, said detecting means comprising a radiation-transmitting device and a radiation-receiving device and said part comprising one of said devices, and means supporting said bracket on said rockshaft.

4. In a delivery mechanism of a printing press wherein sheets being delivered from the press are dropped onto a delivery elevator to stack the sheets into a pile on the elevator and wherein the elevator is to be lowered whenever the pile is built to a predetermined level, the method of sensing when the pile is built to the predetermined level comprising directing a beam of radiation at said level across a corner of the pile being formed and signalling the lowering of the elevator when the pile breaks the beam of radiation.

5. In a printing press delivery including an elevator on which the sheets being delivered are stacked to form a pile and wherein the elevator is lowered When the sheets are stacked to a predetermined level, pile level detecting means for effecting the lowering of the elevator when the pile reaches a predetermined level comprising a radiation-emitting device supported at said level adjacent one side of and at one corner of the pile being formed, a radiation-sensitive device supported adjacent said corner at the side of the pile which defines said corner with the first-mentioned side of the pile, said radiation-emitting device directing a beam of radiation to said radiation-sensitive device.

6. In a delivery mechanism including the structure set forth in claim 5 and wherein said sheets are stacked against guide means disposed along one of said sides of said pile.

7. In a printing press delivery including an elevator on which the sheets being delivered are stacked to form a pile and wherein the elevator is lowered when the sheets are stacked to a predetermined level, pile level detecting means for eilecting the lowering of the elevator when the pile reaches a predetermined level comprising a radiation-emitting device supported at said level adjacent one side of and at one corner of the pile being formed, a radiation-sensitive device supported adjacent said corner at the side of the pile which defines said corner with the first-mentioned side of the pile, said radiation-emitting device directing a beam of radiation to said radiation-sensitiv device, relay means actuatable t0 efiect a lowering of said elevator upon the breaking of said beam, and electric circuit means interconnecting said radiation-sensitive device and said relay means to actuate the latter upon the breaking of said beam and including a capacitor rendering said relay means substantially insensitive to a momentary breaking of said beam.

No references cited. 

